@henfri A example 3rd Party Rock-on was referenced by @OpenSourceUser in a recent forum post. That one was the official Emby Rock-on maintained within their Emby.Build repo. That might be worth a look.
The log file you need to tail is rockstor.log.
Note that this feature is only available in the testing channel updates currently though soon to be released in the stable channel update very soon. At least that was my understanding.
Hope that helps.